Hugh Herr's New Parts

At MIT, making "biohybrids," or prostheses that blur the line between human and device

YOU CAN BARELY hear him over the hum of the machines, a low thrumming that is general throughout the halls and laboratories of the Massachusetts Institute of Technology. You have to lean forward a little when Hugh Herr talks about the arms and legs that he makes here in the MIT Media Lab, during a time in which deceitful politics and bloody bungling have turned the United States into a boom market for prosthetics. Improvements in body armor protect the torso but do nothing for the limbs, and hundreds of Americans have now returned from the excellent adventure in Mesopotamia with less of themselves than they took over there. Which is partly why there is a sudden boom of interest in the work that Hugh Herr is doing in his quiet way in the hush of his lab, and generally in a culture in which informed awareness of prosthetics had not heretofore advanced a great distance from Captain Ahab.

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"It's an interesting time in history for us," Herr says. "There's a lot of funding now for prosthetics. Over the past several years, some critical areas relative to prosthetics have matured--tissue engineering, robotics machinery, the field of neuroprostheses. We've begun to blur the boundaries between humans and devices, and that will lead to a profound clinical effect for people with physical disabilities."

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In the past six years, among its other breakthroughs, Herr's Biomechatronics Group at MIT has developed a prosthetic knee that employs adaptive technology in order to fully integrate the device into the natural functioning of the leg. The "Rheo Knee" is a singular accomplishment, and it is the best demonstration of what have come to be called "biohybrids," machines that interface closely with the human machine to which they are attached. What Herr is aiming for is "to develop a strategy for limb replacement that is a true replacement."

That Herr's interest in the field is not purely academic is obvious from the odd angular cast of his own lower body. In 1982, he was an indifferent high school student in Lancaster, Pennsylvania, who was mad for rock climbing. In fact, Herr enrolled in a local vocational school only because it left him enough free time in the day to climb. One day, he was caught in a blizzard on the slopes of Mount Washington in New Hampshire. He lost both legs below the knee to frostbite. A man named Albert Dow died trying to rescue him. After his recovery, Herr went back to climbing so enthusiastically that a national magazine did a cover story on him but concluded that he would wind up an embittered, legless man working in a machine shop. Instead, he channeled the same passion that drove his climbing into the engineering and mathematics that he taught himself during his recuperation. In part, he did so because of a debt he felt he owed to Albert Dow.

"From that experience," he says, "because of Albert Dow, I felt compelled to make the best of it."

At the beginning, his work dealt primarily with elderly patients, most of whom had lost limbs to diabetes. Now, though, Herr's work is partially funded through the Veterans Administration. "At Walter Reed you see all these young guys who are in top physical shape and who are very motivated," he says. "We're looking at how we can build limbs that are more robust, that don't break as easily, and that allow faster locomotion." Some of Herr's patients already have brought his prostheses back to the war zone with them.

"There's an odd dialogue in this world," he muses. "You say things like, 'Well, I forgot my foot,' and it doesn't compute for some people." Recently Herr developed a prosthesis that suits him. It is a long, slender rod connected to something that looks very much like a tiny stock-car engine atop a flat artificial foot. With a small smile, Hugh Herr walks across the quiet laboratory over to where his new ankle is.